Air oscillator



R. L. WILLIAMS 1,960,25

AIR OSCILLATOR Filed Aug. 5, 1931 INVENTCR fiaerf L. MY/fams ATTORN Y Patented May 29, 1934 i UNITED STATES AIR OSCILLATOR Robert Longfellow Williams, Newton, Mass., as-

signor to Submarine Signal Company, Boston, Mass., a corporation of Maine Application August 3, 1931, Serial No. 554,618

3 Claims. (Cl. 177-7) The invention described in the present specification relates to a means for producing sounds and more particularly to a means for producing sounds of great volume either in air or in water for signaling or other purposes.

The device of the present invention is more particularly directed to fog signals and to that class of fog signals which are operated electrically at a definite frequency and are sometimes known as air oscillators. Oscillators of this type have been built which provide as great a range of signaling as any other type of sound producers. Oscillators operated electrically by the vibration of a diaphragm are probably the most eflicient sound producers and can be operated with a much smaller power plant than most of the fog or warning signals now used.

Due to the fact that oscillators of this nature are usually provided with a horn, the sound produced by such a unit is apt to have a considerable directive effect which might be objectionable in certain places. Further, of course, the fact that these oscillators have a longer range in one direction than in another makes it difiicult to use them under all conditions or in all places.

' Particularly where a uniform distribution is desired such oscillators can not be advantageously employed on lightships.

In the present invention I have devised an air oscillator which has uniform distribution about its entire circumference and may radiate equally effectively and uniformly in all directions in a horizontal plane. Further, the oscillators are so constructed that they may be used in units spaced at most advantageous distances apart to concentrate their radiation in the horizontal plane concentric with the line through the units themselves.

In the present invention the oscillator is provided with two opposed diaphragms which move with the same pressure phase, that is, the diaphragms move outwardly together and inwardly together so that at the same instant they are both compressing or rarefying the sound medium. The diaphragms in the present invention and the horn in which the diaphragms operate are so arranged that for the entire horn the sound has the same compressional phase. The horn is arranged symmetrically with the diaphragms, and the sound energy is propagated simultaneously horizontally in every direction.

The invention will be more fully understood from the description of the apparatus given in the drawing in which Fig. 1 shows a section through a single unit, and Fig. 2 shows a side view of a group of units used together.

In Fig. 1 the oscillator is composed of two circular diaphragms 1 and 2 having heavy inwardly extending rims 8 and 4 which are fixed to each other with a central ring or cylinder 5 bethe obliquely cut poles 6 and '7 in which the coil 8 is placed for energizing the magnetic system.

The pole 6 is attached through the boss 9 in the center of the diaphragm 2, and by this means is held fast to the diaphragm. The pole 7 is similarly attached to the diaphragm 1. The construction of the inside of the oscillator is of the type described in my application Serial No. 502,150 filed December 13, 1930, and for more detailed description of this part of the oscillator I referto that application. v

Mounted on the rims 3 and 4 are the elements 10 and 11 which are composed of cover portions 12 and 13, the outer rims 14 and 15 of which are attached to fit on rims 3 and 4. These cover portions 12 and. 13 are held fast to the oscillator casing by means of bolts 1616 and 171l spaced about the rims 14 and 15 of the covers 12 and 13. The covers 12 and 13 form with the diaphragms 1 and 2, respectively, chambers 18 and 19 whose volume is such that the whole oscillator is resonant to the desired frequencyorifices 20 and 21 for the passage of sound from the diaphragms 1 and 2 are provided in the covers 12 and 13. Spaced about the covers 12 and13 are the webs 22-22, 22-22 supporting plate-like elements 23 and 24 fashioned'in section in horn shape as indicated in Fig. 1. The space embraced between the horn elements 23 and 24 is designed to radiate the sound of the oscillator in all directions in a horizontal plane. The lower horn element 24 may be made integral with supporting webs 25-25 joined at their bottom to the base 26 for supporting the whole unit.

As shown in Fig. 2 the webs 25 and supporting base 26 may be omitted and the units may rest one upon the next, the. lower unit having asupporting base similar to the one described in connection with Fig. 1. In Fig. 2 are shown two units 30 and 31, the unit 30 having a 360 degree sound horn with no supporting base and having its lower horn element 33 resting on the top horn element of the unit 31.

As many units as desired may be used in the arrangement shown in Fig. 2 and by properly spacing the units in a vertical direction practically all the sound energy traveling along the vertical axis of the units may be eliminated, and at the same time a uniform horizontal distribution of the sound may be obtained.

Having now described my invention, I claim:

1. A device for producing sound waves of great intensity comprising a flat casing having diaphragms positioned on opposite parallel faces thereof, means for operating said diaphragm in the same compressional phase, means forming chambers over each of said diaphragms, said chambers having center openings,- and means 3. A device for producing sound waves of great intensity comprising a fiat casing having diaphragms positioned on opposite parallel faces thereof, means for operating said diaphragms in the same compressional phase, means forming chambers over each of said diaphragms, said chambers having center openings, and conical covers positioned over each of said openings, said covers having the vertices thereof extending towards one another and towards the central openings, the covers forming a 360 degree horn radiating in the direction of the surface of the diaphragms.

- ROBERT LONGFELLOW WILLIAMS. 

